device for fjerrstyrt bust and franslag of electrically operated nordningar by phone

摘要

The control appts. is positioned adjacent to the receiving telephone appts., and contains a part which receives predetermined signals via the telephone connection, and when specific conditions are fulfilled emits an output signal. A changeover unit dependent upon the output signal, changes between switch-on and switch-off positions. The receiver part detects ringing signals emitted from the transmitting telephone appts. via the telephone connection, and on receipt of a predetermined ringing signal combination activates the changeover unit. - The ringing signal combination comprises a specific number of signals for a series followed by a specific number of ringing signals for one or more further series. Each further ringing signal series occurs after a primary time interval subsequent to the previous ringing. (Provisional basic advised week 89/05)